A Hybrid Current Balancing Method for Multiple Paralleled SiC-MOSFET Half-bridge Modules

The parallel connection of SiC-MOSFET modules can effectively increase the rated current of modules, however, the related current imbalance issue will affect the performance of the system. To solve this problem, this paper proposes a hybrid current balancing method for multiple paralleled SiC-MOSFET half-bridge modules, which can balance the transient current and steady-state current of the modules, simultaneously. Firstly, the operating principles of the current balancing circuit are analyzed, and multiple toroidal magnetic cores with additional windings and DC current compensator are utilized to suppress the transient imbalance currents. Then, a novel current detection circuit is introduced to capture the steady-state imbalance current of the modules. Based on the obtained unbalanced currents, the steady-state currents of the modules are finally balanced by using a closed-loop active PWM edge regulation method. The proposed hybrid current balancing method does not require high-bandwidth high-precision current sensors and introduces negligible reactive power to the system. It can be easily extended to more paralleled modules and employed in DC/DC converters. The effectiveness of the proposed method is experimentally verified by a prototype with three paralleled 1200V/120A SiC-MOSFET half-bridge modules. The results show that with the proposed method, both the transient current and steady-state current are well balanced.